Variable condenser



May 9, I

A. S. KESTER VARIABLE CONDENSER Filed Jan. 8, 1942 2 Sheets-Sheet 2 U I 49 11 J? ATTORNEY Patented May 9, 1944 VARIABLE CONDENSER Arthur S. Kester, Chicago, Ill., assignor to The Rauland Corporation, Chicago, 11]., a corporation of Illinois ApplicatiomJanuary '8, 1942, Serial No. 425,987

6 Claims.

This invention relates to new and useful improvements in variable condensers.

Among the objects of the present invention are the adjustability of a variable condenser with a high degree of precision, simplicity and sturdiness of construction, and the possibility of mounting the condenser assembly without regard to slight inequalities in the mounting panel.

With these and other objects in view, I shall now describe a preferred embodiment of the inventionwith reference to the drawings, in which Fig. 1 is a side elevation with parts broken away;

Fig. 2 is another side elevation, partly in section;

Fig. 3 is a cross section alon lines 3-3 of Fig. 1;

Fig. 4 is a perspective exploded view of the main frame;

Fig. 5 is a perspective view of the disc for absorbing the axial thrust on the main bearing; and

Fig. 6 is a perspective view of a resilient bearin seat for the transverse driving shaft;

The main frame around which the whole-condenser is built will first be described with reference to Fig. 4. The frame is die cast and has a front wall I and two spaced transverse wings, 2 and 3. The front wall has a central window opening 4 and a hollow boss 5. The wings are perfo-' rated at 6' and I and have their corners cut off to form square shoulders indicated at 8 and 9. The upper part of the front wall slopes back as indicated at In and from this project two internally screw-threaded bushings, H and I2, the ends of which are in alignment with a shorter internally screw-threaded bushing 13 projecting from the lower edge of the front wall. ll, l2, and 13 are the three points by which the whole condenser can be mounted on a plate or any other supporting surface. Thus, distortion will be avoided when the mounting panel is uneven.

The condenser proper consists of rotor plates l6 mounted on a long sleeve l5 and cooperating with stator plates M which are fastened by means of screws ll between two opposite strips of insulation, one of which is shown at |B= in Fig. 1. One end of strip i8 is fastened by a screw 19 to the shoulder B of the main casting and the other end to a shoulder-of an end plate 20. The other insulating strip is not shown in the drawing but it is fastened to the shoulder 9 of wing 3;

and a corresponding shoulder formed in the end plate 20.

A similar condenser stator and rotor assembly is provided on the left-hand side of the main casting (Figs. 1 and 2) and whatever is said of one portion of the condenser applies to the other also.

The sleeve 15 surrounds one end of a single solid shaft 2| which traverses the whole length of the condenser through openings 6 and I in the wings 2 and 3. The sleeve is held in position by means of a pin or set screw 22 engaging the ends of the rotor sleeve I5.

In each of the openings 6 and l, the shaft 2| is provided with a ball bearing 23. The end plate 20 is held in position by means of two spacing rods, only one of which is shown in Fig. 2 at 24 and the two ends of which are screwed into the .end plate and the wing 3 of the main casting, respectively. A similar end plate is fastened to wing 2 on the other end of the condenser.

Both end plates are die cast.

ings mounted near its center between the two sets of rotors, perfect alignment of the shaft is assured at all times without any strains as would be the case if the shaft were supported at its two ends alone or by one or two bearings near its center and bearings engaging the ends. Not only will such central support avoid warping of the shaft,- but it will materially reduce friction, one of the main causes of backlash.

Between thectwo wings 2 and 3 of the main casting, the shaft 2| carries a gear 25 provided with a hub 26 pinned to the shaft at 21; also a semi-circular casting 28 provided with a numbered dial or scale and a casting 29 rotatably mounted on a hub 30 of the casting 28. The casting 28 is fastened to the shaft 2| by means of set screws. As shown in Fig. 2, the edge of the casting 29 which is visible through the window 4 has a reference line 3| cooperating with the scale on the dial 28. The position of the casting 29 and, therefore, of the reference line 3| is determined by a set screw 32 (Figs. 1, 3, and 4) against which 29 is pulled by a coiled spring 33.,

' The set screw projects through an ear 34 of a die cast cross support which is fastened to the wings 2 and 3 of the main casting by screws passing through holes 35, 3B, and 31. One end of the coiled spring 33' is attached to the quadrant 29 and the other end to the cross support below the set screw 32.

The arrangement of the main casting affords room for a driving gear 25, dial 28, and index quadrant 29 of large diameter. This will make easier correct setting of the condenser.

Since the main shaft of the condenser is of one piece and is supported only by two ball bear shaped seat 49 for ball 50.

The rotors of the condenser together with the dial 28 may be rotated by turning a knob 40 fastened to one end of a transverse driving shaft 4|. A dial 39 is integral with knob 40 and serves to indicate the angular displacement of shaft 4|. The driving shaft projects through the bushing in the main casting and it is provided intermediate its ends, with a worm 42 which is in engagement with the teeth of the helical gear 25 so that when the shaft 4| is rotated, it will cause rotation of the gear 25, The teeth of ear 25 and the worm 42 are wedge-shaped and, since the two are pressed against one another by means of a coiled spring 43, in a manner to be presently described, backlash is definitely prevented even after considerable wear in the parts.

The free end of shaft 4| passes through a square bearing 44 which is held within but free to move with respect to the C-shaped end 45 of the vertical limb 46 in the cross support. The bearing 44 is fastened to one end of coiled spring 43, the other end of which is wrapped around an adjusting screw 41 in the cross support. The bearing 44 is prevented from slipping off the end of the shaft 4| by a ring 48 seated in a groove near the end of the shaft, and its movement in the opposite direction along the shaft 4| is prevented by a shoulder 49 formed in the latter.

It will be seen that, except for the resilient restraint exercised by the adjustable spring 43, the end of the shaft 4| has a limited freedom of movement up and down and also in an axial directlon. This limited movement is made possible by the manner in which the other bearing of the shaft 4| is provided in the bushing 5. The portion of the shaft within the bushing has a ball 50 formed therein. The ball engages a bronze cup bearing 5| set in the bottom of the bushing and a removable coiled bronze bearing 52 surrounding the shaft within bushing 5 and having a cup- The angles on the bearings 5| and 52 which touch the worm shaft ball 50 are so arranged that there is no torque apparent when operating force is removed from knob 40. This is obtained by having the line of contact between bearing 5| and the worm shaft ball 50 of a larger diameter than that between bearing 52 and the worm shaft ball. The end 53 of bearing spring 52 is turned at right angles and projects through a hole in a washer 54 screwed over the open end of the bushing 5. The bearing 52 is thus held against rotation.

The two resilient bearings of the transverse shaft will insure against backlash in the coupling with the main shaft without the necessity of providing complicated split driving gears and the like.

The end thrust in the main shaft 2| is absorbed by the use of a suitable spring 6| which bears against wing 3 and has fingers 65 (Fig. 5)

pressing on the outside race of the ball bearing 23. The spring washer 6| is held in position by a rigid washer 52 fastened to wing 3. A washer 66 of Bakelite or other suitable material is inserted between the bearing and the inside face of this spring washer, thus preventing over strain on the fingers when the unit is dropped on its end.

The rotor assembly l6, |5 of the condenser is grounded through a beryllium copper spring 63 which is soldered to rivets G4 traversing end plate and connected to suitable external lugs.

The condenser is enclosed within metallic housing 65 fastened to the main casting and the end plates by screws.

The completely assembled condenser may be mounted by screws which engage the three bushings II, I2, and I3. This mounting may be, as shown in Figs. 1 and 2, on a plate 56 by means of screws 51, 58, and 59, the plate 56 being in turn mounted on a surface at six points 60. There is no strain transmitted to any other portion of the condenser than to the massive main casting.

It will be obvious to those skilled in the art that'many modifications are possible without departing from the spirit of the invention, and that some of the features described may be used separately or in combination with other variable condenser structures.

What is claimed is:

1. In a drive for variable condensers and the like, a main shaft, two ball bearings constituting the sole bearings for the shaft near the center thereof, a driving gear fastened to the shaft between the two bearings, a transverse driving shaft having a worm engaging said gear, a bearing for one end of the transverse shaft, a resilient suspension for the last-mentioned bearing, allowing movement thereof substantially at right angles to the longitudinal axis of the transverse shaft, and a resilient bearing near the other end of the transverse shaft holding it against transverse movement but allowing limited movement about a fixed point.

2. In a drive for variable condensers and the like, a main shaft, two bearings for the shaft near the center thereof, a driving gear fastened to the shaft between the two bearings, a transverse driving shaft having a worm engaging said gear, an adjustable spring-pressed bearing for one end of said transverse shaft, a ball formed in said transverse shaft near the other end thereof, a cupped seat for said ball, and a spring coiled around said transverse shaft and having a second seat for said ball.

3. In a drive for variable condensers and the like, a shaft, driving means for said shaft, an indicating dial fastened to said shaft, a reference dial rotatable with respect to said indicating dial, an adjustable stop for said reference dial and a spring holding said reference dial,

against said stop.

4. In a drive for variable condensers and the like, two sleeves, a frame having a front wall and two spaced transverse wings, a main shaft projecting through the wings and carrying on its two free ends said sleeves fastened thereto, a bearing for the shaft in each wing, a driving gear fastened to the shaft between the two wings, an indicating dial fastened to the shaft between the two wings, a transverse worm shaft at right angles to the main shaft and engaging with its worm the gear, a resilient bearing near one end of said transverse shaft in said frame, and a spring-supported bearing for the other end of said transverse shaft.

5. In a drive for variable condensers and the like, two sleeves, a casting having a front wall and two spaced transverse wings, the front wall having a window and three mounting points, and

the wings being perforated, a main shaft pro-' jecting through the perforations in the wings and carrying on its two free ends the sleeves fastened thereto, a ball bearing for the shaft in each wing, a driving gear fastened to the shalt between the two wings, an indicating dial fastened to the shaft between the two wings and visible through the window, a transverse worm shaft at right angles to the main shaft and engaging with its worm the gear, a resilient bearing near one end of said transverse shaft in said casting, a slidable bearing for the other end of said transverse shaft in said casting, and a coiled spring engaging said slidable bearing and pulling the worm of the transverse shaft into engagement and carrying on its two free ends the sleeves fastened thereto, a ball bearing for the shaft in each wing, a driving gear fastened to the shaft between the two wings, an indicating dial fastened to the shaft between the two wings and visible through the window, a reference dial rotatably mounted on said main shaft between said wings, an adjustable stop for said reference dial, a spring holding said reference dial against said stop, a transverse worm shaft at right angles to the main shaft and engaging with its worm the gear, a ball formed near one end of said transverse shaft, a rigid and a resilient seat for said ball in said casting, a slidable bearing for the other end of said transverse shaft in said casting, a coiled spring engaging said slidable bearing and pulling the worm of the transverse shaft into engagement with said gear, and end plates mounted on said wings spaced therefrom.

ARTHUR S. KESTER. 

